The Cobol compiler I used had special coding requirements for external
routines. There was a "linkage section" (I think it was like a common
block) and an "enter linkage" statement to make or receive the
subroutine call. You couldn't enter the code at an arbitrary
paragraph. It wouldn't surprise me to discover that the entry point
names were restricted to 6 or 8 characters, in contrast to most other
cobol identifiers.
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